The invention relates to a process for thermal salvage of waste materials containing organic components as well as a device for the thermal preparation of such waste.
The removal of waste materials containing organic components, such as domestic waste, industrial waste, etc., is at the present time as a rule performed by transport to waste dumps or through burning. The dumping of unsorted waste is very complex and may create new environmental burdens which may e.g. endanger ground water if the dumping grounds are not prepared properly. The establishment of new dumping grounds is also becoming more and more difficult because of permit laws. The dumping of trash or waste is also to a certain degree contrary to the legal stipulation of salvaging waste materials.
One possibility to avoid or reduce dumping problems is the thermal salvaging of waste materials to generate steam and electricity. In this context we already know of grate furnaces in which the waste materials are burned in the state they arrived in. In order to ensure continuous operation of these plants a larger-scale intermediate storage is inevitable if the waste is delivered discontinuously. This results in fermentation and decay processes and thus in odor developments offensive to the surrounding area.
In addition, because of e.g. the sometimes great fluctuations of the waste thermal value the combustion in such grate furnaces is as a rule rather inhomogeneous. This results in relatively high non-burned shares in the slag and fly-ash. This incomplete combustion results in odor problems even in the ash and such ash is in comparison with the ash of e.g. a hard coal power plant much harder to dispose of. Sometimes these ashes must be transported to removed special dumping grounds at high costs. Because of the incomplete combustion it can also not be excluded that highly toxic dioxines, e.g. polychlorinated dibenzodioxine or even polychlorinated dibenzofuranes may be generated if the waste materials contain organic or also inorganic chlorine compounds, e.g. polychlorinated biphenyls (PCB).